U.S. patent number 6,732,959 [Application Number 10/234,285] was granted by the patent office on 2004-05-11 for dual-coil outwardly-opening fuel injector.
This patent grant is currently assigned to Delphi Technologies, Inc.. Invention is credited to Kevin J. Allen, John H. Delaney, Noreen L. Mastro, Robert B. Perry, Jay K. Sofianek, Joseph G. Spakowski, Daniel L. Varble.
United States Patent |
6,732,959 |
Delaney , et al. |
May 11, 2004 |
Dual-coil outwardly-opening fuel injector
Abstract
A dual-coil outwardly-opening fuel injector including a fuel
tube connected at a lower end to a lower injector housing. Within
the fuel tube are a lower (opening) solenoid pole piece, a
specially-formed armature, and an upper (closing) solenoid pole
piece. A seat assembly including an injector nozzle, swirler, and
valve seat are adjustably threaded into the lower housing. A pintle
assembly, including a solid pintle portion supporting a valve head
and a tubular portion welded thereto, is axially disposed within
the fuel tube and is welded to the armature which is spaced from
the lower pole piece by a distance equal to the opening stroke of
the valve. A return spring adjustment mechanism disposed on the
upper pole piece engages the upper end of the pintle assembly for
varying the closing force of the return spring. Opening and closing
solenoid preassemblies are mounted external to the fuel tube for
magnetically engaging the pole pieces and armature within in known
fashion.
Inventors: |
Delaney; John H. (Scottsville,
NY), Spakowski; Joseph G. (Rochester, NY), Mastro; Noreen
L. (Spencerport, NY), Perry; Robert B. (Leicester,
NY), Varble; Daniel L. (Henrietta, NY), Allen; Kevin
J. (Avon, NY), Sofianek; Jay K. (Webster, NY) |
Assignee: |
Delphi Technologies, Inc.
(Troy, MI)
|
Family
ID: |
31977392 |
Appl.
No.: |
10/234,285 |
Filed: |
September 4, 2002 |
Current U.S.
Class: |
239/585.1;
239/585.3; 239/585.5; 251/129.1 |
Current CPC
Class: |
F02M
51/0621 (20130101); F02M 61/06 (20130101); F02M
61/08 (20130101); F02M 61/162 (20130101) |
Current International
Class: |
F02M
61/06 (20060101); F02M 61/08 (20060101); F02M
61/00 (20060101); F02M 61/16 (20060101); F02M
51/06 (20060101); B05B 001/30 () |
Field of
Search: |
;239/585.1,585.2,585.3,585.5 ;251/129.2,129.09,129.15,129.16 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Nguyen; Dinh Q.
Attorney, Agent or Firm: Griffin; Patrick M.
Claims
What is claimed is:
1. A fuel injector for injecting fuel into an internal combustion
engine, comprising: a) a lower housing element; b) a fuel tube
received in said lower housing element for receiving and conveying
fuel from a pressurized source; c) a seat assembly received in said
lower housing element, including an injector nozzle and an injector
valve seat receivable of fuel from said fuel tube; d) a first
solenoid pole piece disposed in said fuel tube; e) a second
solenoid pole piece disposed in said fuel tube; f) an armature
disposed in said fuel tube between said first and second pole
pieces; g) a pintle including a valve head axially disposed in said
seat assembly and said fuel tube and attached to said armature; h)
a first solenoid assembly disposed around said fuel tube adjacent
said first pole piece for opening said injector valve to dispense
fuel from said injector; and i) a second solenoid assembly disposed
around said fuel tube adjacent said second pole piece for closing
said injector valve.
2. A fuel injector in accordance with claim 1 further comprising:
a) a return spring disposed adjacent said second pole piece and
surrounding said pintle, said pintle extending beyond said second
pole piece; and b) adjusting means disposed in said fuel tube and
engaging of said pintle and spring to adjust the compression of
said spring against said second pole piece.
3. A fuel injector in accordance with claim 2 wherein said
adjusting means is accessible from outside said fuel injector to
perform said adjusting of said spring compression.
4. A fuel injector in accordance with claim 1 further comprising a
load tube disposed around said fuel tube adjacent said second
solenoid assembly.
5. A fuel injector in accordance with claim 1 further comprising a
non-magnetic washer disposed between said first and second solenoid
assemblies.
6. A fuel injector in accordance with claim 1 further comprising a
damping bushing disposed between said first pole piece and said
pintle.
7. A fuel injector in accordance with claim 1 wherein said seat
assembly is attached to said lower housing element by threads to
permit relative axial motion therebetween.
8. A fuel injector in accordance with claim 7 wherein the stroke
length of the injector is adjustable by rotation of said seat
assembly within said lower housing element.
9. A fuel injector in accordance with claim 1 wherein said armature
and said first pole piece are each provided with mating inserted
stops on opposed surfaces thereof.
10. A fuel injector in accordance with claim 1 wherein said
armature and said first pole piece are each provided with mating
conically tapered surfaces for cooperatively shaping a
valve-opening magnetic field.
11. A fuel injector in accordance with claim 1 further provided
with means for engaging with a source of pressurized fuel.
12. A fuel injector in accordance with claim 11 wherein said fuel
is selected from the group consisting of gasoline and diesel
fuel.
13. A fuel injector in accordance with claim 1 wherein said
injector is suited for direct injection of fuel into an engine's
combustion chamber.
14. A fuel injector in accordance with claim 1 wherein said
armature comprises: a) a first element magnetically responsive to
said first solenoid assembly and having a first diameter; b) a
second element magnetically responsive to said second solenoid
assembly and having a second diameter and being spaced apart from
said first element; and c) a tubular connector having a third
diameter less than said first and second diameters and axially
connecting said first and second elements.
15. An internal combustion engine, comprising a fuel injector
including a lower housing element, a fuel tube received in said
lower housing element for receiving and conveying fuel from a
pressurized source, a seat assembly received in said lower housing
element, including an injector nozzle and an injector valve seat
receivable of fuel from said fuel tube, a first solenoid pole piece
disposed in said fuel tube, a second solenoid pole piece disposed
in said fuel tube, an armature disposed in said fuel tube between
said first and second pole pieces, a pintle including a valve head
axially disposed in said seat assembly and said fuel tube and
attached to said armature and extending beyond said second pole
piece, a return spring disposed adjacent said second pole piece and
surrounding said pintle, adjusting means disposed in said fuel tube
and engaging of said pintle and spring to adjust the compression of
said spring against said second pole piece, a first solenoid
assembly disposed around said fuel tube adjacent said first pole
piece for opening said injector valve to dispense fuel from said
fuel injector, and a second solenoid assembly disposed around said
fuel tube adjacent said second pole piece for closing said injector
valve.
16. An armature for a dual-coil fuel injector having first and
second solenoid assemblies, comprising: a) a first element
magnetically responsive to said first solenoid assembly and having
a first diameter; b) a second element magnetically responsive to
said second solenoid assembly and having a second diameter and
being spaced apart from said first element; and c) a tubular
connector having a third diameter less than said first and second
diameters and axially connecting said first and second elements.
Description
TECHNICAL FIELD
The present invention relates to direct injection fuel injectors;
more particularly, to such fuel injectors having both opening and
closing solenoid actuators; and most particularly, to such a fuel
injector having reduced size, lower component cost, fewer assembly
steps, lower material cost, single flow assembly, and external
calibration.
BACKGROUND OF THE INVENTION
Outwardly-opening fuel injectors are well known for use in
injecting fuel into the combustion cylinders of internal combustion
engines. Such injection is known in the art as "direct injection"
as opposed to "port injection" wherein fuel is injected into a
manifold port upstream of the cylinder's intake valve.
An especially demanding use of direct injection is for injection of
gasoline into spark-ignited internal combustion engines. Engine
manufacturers are now recognizing that so-called "spray-guided"
fuel injectors can be important factors in meeting fuel emission
and fuel economy standards. Spray guided means that the fuel is
injected into the combustion chamber and presented to the spark
plug for ignition as an atomized fuel cloud having the proper
location, size, and shape. The actual combustion chamber itself is
not required to deflect, relocate, or prepare the fuel for
ignition. For spray guided combustion, it is very important that
the spray geometry remains consistent throughout a wide range of
engine operating conditions. A known method of achieving the spray
guided function is to cause the fuel injector to open outwardly
into the firing chamber and to use the valve head to shape and
direct the fuel exiting the injector.
U.S. Pat. Nos. 6,036,120, issued Mar. 14, 2000, and 6,065,684,
issued May 23, 2000, are drawn to apparatus and method,
respectively, for a direct injection fuel injector and are both
incorporated herein by reference. The specifications are identical,
and the two patents are treated here as a single disclosure. A high
fuel pressure exerting an opening force is slightly overbalanced by
a return spring tending to close the valve. A first solenoid acts
to open the valve against the excess return spring force and a
second solenoid acts to close the valve when the first solenoid is
de-energized. Rapid valve closing is provided by energizing the
second solenoid before de-energizing the first solenoid, the force
of the second solenoid when the valve is open being insufficient to
overcome the force of the first solenoid holding the valve open.
Thus, the second solenoid magnetic force is fully developed and
quickly closes the injection valve when the first solenoid is
de-energized.
The prior art fuel injector has several drawbacks relating to final
size, placement of the solenoids within the fuel flow path, and
ease of assembly.
What is needed in the art is a dual-coil, outwardly-opening fuel
injector having fewer components, solenoids outside a fuel tube,
and which is easier to assemble.
It is a principal object of the present invention to reduce the
size and cost of an improved dual-coil outwardly-opening fuel
injector.
It is a further object of the present invention to simplify the
assembly of such an improved fuel injector.
It is a still further object of the present invention to provide
for external calibration of the return spring of such an improved
fuel injector.
SUMMARY OF THE INVENTION
Briefly described, a dual-coil outwardly-opening fuel injector
includes a fuel tube connected at a lower end to a lower injector
housing. Within the fuel tube are a lower (opening) solenoid pole
piece, a specially-formed armature, and an upper (closing) solenoid
pole piece. A seat assembly including an injector nozzle, swirler,
and valve seat are adjustably threaded into the lower housing. A
pintle assembly, including a solid pintle portion supporting a
valve head and a tubular portion-welded thereto, is axially
disposed within the fuel tube and those components and is welded to
the armature which is temporarily spaced from the upper pole piece
by a distance equal to the opening stroke of the valve. The seat
assembly is then turned into the lower housing, moving the armature
away from the lower pole piece and into contact with the upper pole
piece, thus setting the stroke of the valve. A return spring
adjustment mechanism disposed on the upper pole piece engages the
upper end of the pintle assembly for varying the closing force of
the return spring. Opening and closing solenoid preassemblies are
mounted external to the fuel tube for magnetically engaging the
pole pieces and armature within in known fashion.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be described, by way of example,
with reference to the accompanying drawings, in which:
FIG. 1 is an elevational cross-sectional view of a prior art
dual-coil outwardly-opening fuel injector;
FIG. 2 is an elevational cross-sectional view of a novel dual-coil
outwardly-opening fuel injector in accordance with the
invention;
FIG. 3 is a detailed cross-sectional view of an optional embodiment
of the armature and lower pole to include hardened, centering
stops; and
FIG. 4 is a cross-sectional view of an alternative embodiment of
the armature and lower pole, showing tapered conical mating faces
thereupon for shaping the opening magnetic field.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The novelty and advantages conferred by the invention may be better
appreciated by first considering a prior art dual-coil
outwardly-opening fuel injector.
Referring to FIG. 1, a prior art fuel injector 10, substantially
the same as is disclosed in U.S. Pat. No. 6,065,684, is formed from
two assemblies, including an upper housing assembly 12 and a lower
housing assembly 14. The upper housing assembly 12 includes an
upper housing 16 having an inlet defined by a threaded fuel fitting
18 and communicating through an inlet passage 20 containing a fuel
filter 22 with a chamber or recess containing an upper solenoid
assembly 24.
Lower housing assembly 14 includes a lower housing 26 having an
enlarged upper portion 28 and a smaller diameter tubular lower
portion 30. The upper portion has an outer diameter that is
received in a generally cylindrical recess 32 formed in the lower
portion of upper housing 16. A lower solenoid assembly 34 is
received in an upwardly opening recess of the lower housing upper
portion 28. Terminals 36,38 extend upward from the lower and upper
solenoids 24,34 respectively through openings in the upper housing,
16 which are sealed by O-ring seals 40.
The upper solenoid assembly 24 includes a generally cylindrical
upper soft (not permanently magnetized) magnetic pole 42 with a
central axial passage 44 and a radial or transverse upper groove
46, both connecting with the fuel inlet passage 20. Groove 46
further connects with longitudinally extending external side
grooves 48 leading to the lower end of the pole. An annular recess,
opening to the lower end of pole 42, receives an upper solenoid
coil 50 wound on a non-magnetic bobbin 52 having an annular upper
groove for connection of the coil with its terminals 38.
The lower solenoid assembly 34 also includes a generally
cylindrical lower soft magnetic pole 54 having an axial central
bore 56 and a radial or transverse groove 58 across its lower side
and connecting with external longitudinal side grooves 60 extending
to the upper end of the pole. An upwardly opening annular recess in
the pole 54 receives a lower solenoid coil 62 also wound on a
non-magnetic bobbin 64 having an upper groove for connecting the
coil through a slot in the side of the bobbin with the terminals 36
leading from the lower coil.
Located between the magnetic poles 42,54 is a disc-like armature 66
also formed of a soft magnetic material. The armature 66 has a
central opening through which extends a pintle 68 having a
retaining nut 70 threaded onto one end of the pintle. The nut 70
holds the armature 66 against the upper end of a tubular portion of
a spring upper guide 72. The armature, 66, pintle 68, pintle nut
70, and guide 72 form an armature assembly, the parts of which are
fixed together by the nut for movement in unison.
Guide 72 acts as a tubular valve guide for the upper end of the
pintle 68 which extends therethrough and beyond to the lower end of
the lower portion 30 of the lower housing 26. An injector nozzle 74
is threadably mounted in the lower end of lower portion 30 and has
a centrally located outwardly opening conical valve seat 76 which
is engageable by a conical valve element 78 formed on the lower end
of the pintle which acts as a pintle valve. A swirl generator 80 is
located around the pintle within the injector nozzle 74 defining
therewith passages which impart a swirl motion to fuel passing
therethrough toward the valve seat 76. The lower end of the spring
upper guide 72 forms a spring seat for a helical return spring 82
which extends downward in the lower portion 30 of the lower housing
to a lower spring guide 84 that seats against the injector nozzle
74. During assembly, the spring is compressed to the desired force
and the upper guide 72 is then welded to the pintle to maintain the
return spring force.
Additional components of the injector 10 include a housing seal 86
and an injector nozzle seal 87 to prevent leakage of fuel from the
housing 16,18. The pintle retaining nut 70 is received in a recess
in the lower end of the upper pole 42 and forming a part of the
axial passage 44. A similar recess in the upper end of the lower
pole 54 receives a hardened stop 88 which is engaged by an armature
stop 90 to provide a predetermined gap or clearance between the
armature 66 and the lower pole 54 when the stops are engaged. The
armature stroke is set by turning the threaded nozzle 74 with the
valve closed until the spacing of the armature from the stop 88 is
equal to the desired stroke. A spacer ring 92 is located between
the upper end of the lower housing 26 and a downwardly facing
annular abutment in the recess 32 of the upper housing 16. The
spacer ring 92 is sized longitudinally after setting the stroke to
provide a predetermined clearance or gap between the armature and
the upper magnetic pole when the valve 78 is closed. Relief holes
94 extend axially through armature 66 to prevent hydraulic damping
of armature motion by the fuel in which it is immersed.
Prior art fuel injector 10 has a number of drawbacks which are
overcome by the present invention. Injector 10 is cumbersome to
assemble and calibrate. Because of normal manufacturing variability
in dimensions of components, setting the stroke precisely and
selecting the correct size for spacer ring 92 can require partial
disassembly and reassembly of the injector, sometimes more than
once. The fuel flow path is not via a single metal tube, as is
known in the art of port-injection fuel injectors, and thus fuel
may leak past seals 86 and 40; fuel is provided within a
direct-injection fuel injector at pressures of, typically, about
1500 psi. Further, because the spring is welded to the pintle at a
predetermined degree of compression, the spring force is not
adjustable after assembly to accommodate various fuel pressures
which may be encountered in different applications. The solenoids
are built within the housings and are fully immersed in the fuel
flowpath, which is undesirable and can be dangerous. In operation,
armature 66 is subject simultaneously to opening and closing
magnetic fields, with magnetic cross-over between the fields.
Referring to FIG. 2, components identical with or analogous to
components shown in FIG. 1 are indicated by the same numbers
primed. An improved dual-coil outwardly-opening fuel injector 10'
in accordance with the invention, for use with an internal
combustion engine 200, includes a main fuel tube 102, formed of a
non-magnetic material such as stainless steel, which joins to lower
housing components 104,106 via an annular weld 108. If desired,
components 104,106 may be provided as a single element. The fuel
flow path is completely contained within this structure and flows
primarily along the inner wall of the tube outboard of the solenoid
pole pieces as well as along the pintle assembly over a portion of
the path. Within fuel tube 102, a disc-shaped pintle guide 103 is
pressed into component 106 against first stop 105. Guide 103 has an
axial bore for guiding a pintle as described below and also has
axial passages for flow of fuel therethrough. Lower (opening)
magnetic pole 54', having an axial bore 56', is pressed into
housing component 106 against second stop 110.
A generally cylindrical armature 66' having an axial bore 112 is
disposed within tube 102 adjacent pole 54'. Armature 66' preferably
is formed as upper and lower armature elements 66'a,66'b having
substantially identical first and second diameters, respectively,
and separated by a washer-shaped air gap 114 and axially connected
by a slim connector tube 116 having a third diameter less than the
first and second diameters to minimize flux leakage between the
upper and lower armature elements. Thus, the armature can function
as a single element mechanically, responsive as a unit to both
solenoids, but as two substantially separate elements magnetically,
upper element 66'a being responsive to the closing solenoid and
lower element 66'b being responsive to the opening solenoid, as
described below.
An upper (closing) magnetic pole 42', having an axial bore 44', is
disposed within tube 102 adjacent armature 66'. Ring-shaped spring
seat 84' is disposed in a well in the upper end of pole 42' for
receiving the lower end of return spring 82'.
A seat assembly 118 comprises injector nozzle 120, swirler 122, and
pintle seat 124, substantially as disclosed in commonly-assigned
U.S. Pat. No. 6,042,028 which is hereby incorporated by reference.
Seat assembly 118 is threadedly received into element 103 via
threads 126.
A pintle assembly 68' having a valve element 78' formed at the
lower end is disposed axially within the assembly 10' as described
thus far. Pintle assembly 68' preferably is formed of a solid
portion 68'a and a tubular portion 68'b joined by a weld 128,
thereby reducing weight and cost of the pintle. A threaded insert
130 is provided at the upper end of portion 68'b for receiving an
adjustment nut 132' which also captures spring 82'.
Lower solenoid assembly 34' is preferably preassembled as a unit to
be slid onto the outside of fuel tube 102 from the upper end.
Assembly 34' includes a non-magnetic bobbin 64' supporting an
opening coil 62', an opening coil body 134, and magnetic spacer
136.
Upper solenoid assembly 24' also is preferably preassembled as a
unit to be slid onto the outside of fuel tube 102 from the upper
end. Assembly 24' includes a magnetic spacer 138, a non-magnetic
bobbin 52' supporting a closing coil 50', and a closing coil body
140. Preferably, upper solenoid assembly 24' is axially spaced
apart from lower coil assembly 34' by a non-magnetic air gap washer
142 having a thickness equal to the height of air gap 114 in
armature 66'. The solenoid assemblies are axially fixed to tube 102
as by adhesives or press fit in known fashion. Load tube 144 and
backup ring 146 are disposed over fuel tube 102 and similarly
attached. This arrangement transfers all axial load transients in
the injector via an outer load shell comprising backup ring 146,
load tube 144, spacers 136,138, coil bodies 134,140, gap washer
142, and lower elements 104,106. Thus, fuel tube 102 may be formed
of quite thin stock, sufficient to withstand high fuel pressures
but thin enough to permit excellent magnetic coupling between the
solenoid assemblies 24',34', the opening and closing poles 42',54',
and the armature 66'.
Improved injector 10' may be conveniently assembled as follows.
Pintle guide 103 is pressed into lower housing component 106.
Preassembled seat assembly 118 is threaded via threads 126 into
component 106 to a stop, then backed out two turns to allow for
later stroke adjustment. Lower pole 54' is inserted into the barrel
of fuel tube 102 and cemented to stop 110. Pintle 68a' is welded to
pintle tube 68'b at weld 128, and threaded insert 130 is welded to
pintle tube 68'b at weld 148. Pintle assembly 68' is inserted into
tube 102 via seat assembly 118. Armature 66' is lowered onto pintle
assembly 68' until in contact with lower pole 54', the pintle valve
being in the closed position, then is welded to pintle assembly 68'
via weld 150. Upper pole 42' is inserted into the barrel of fuel
tube 102 and is welded to the fuel tube via weld 152 at an axial
location such that a gap exists between pole 42' and armature 66'
equal in height to the intended stroke of the valve. Spring seat
84' is inserted onto upper pole 42'. Fuel tube 102 is welded to
lower housing component 104 via weld 108. Seat assembly 118 then is
turned into lower component 106 along threads 126, the valve being
closed all the while, until armature 66' contacts upper pole 42'
which acts as a stop for the armature. The armature is now free to
move between the upper and lower poles by the height of the
incorporated gap, which defines the open and closed positions of
the valve.
Optionally, a pintle retainer 107 may be swaged onto pintle portion
68'a to prevent the pintle portion from exiting the seat assembly
and damaging the associated engine if weld 128 fails.
Optionally, a bushing 111 may be provided between pole 54' and
pintle tube 68'b to retard displacement of fuel from between
armature 66' and pole 54' during actuation of the injector, thus
providing a hydraulic damper for impact of the armature against the
pole. Alternatively, referring to FIG. 3, armature 66' and pole 54'
may be provided with inserted stops 154,156, respectively, formed
of a hard material, for example, carbide. Preferably such stops are
tapered as shown to provide centering guidance of the
armature/pintle assembly in meeting the lower pole.
Referring to FIG. 4, the armature 66' and pole 54' may be provided
with conically tapered mating faces, 158,160, respectively, which
can desirably shape the valve-opening magnetic field to enhance the
valve-opening time profile.
Referring again to FIG. 2, return spring 82' is installed onto
spring seat 84' and is captured by nut 132. The expansive force of
compressed spring 82' holds the valve closed against fuel pressure
within the fuel tube. Thus, nut 132 may be advanced along threaded
insert 130, as by a wrench through the open end of tube 102, to
progressively compress spring 82' and provide any desired amount of
closing force as required by a specific injector use.
Solenoid assemblies 34', 24', washer 142, load tube 144, and backup
ring 146 are installed over fuel tube 102 as described above.
Improved fuel injector assembly 10' may be fitted conventionally to
a fuel rail and sealed thereto via O-ring 148, or alternatively it
may be provided with a threaded nipple attachment 18 as shown for
prior art injector 10 in FIG. 1.
In operation, improved fuel injector 10' functions substantially
identically with prior art fuel injector 10. However, the
manufacturing benefits of the invention are readily seen in a
comparison of manufacturing costs, steps, and components between
prior art injector 10 and improved injector 10':
Injector 10 Injector 10' Process steps 72 37 Hermetic welds 6 3
Number of components 38 21 Cost of materials X 0.5X
While the invention has been described by reference to various
specific embodiments, it should be understood that numerous changes
may be made within the spirit and scope of the inventive concepts
described. Accordingly, it is intended that the invention not be
limited to the described embodiments, but will have full scope
defined by the language of the following claims.
* * * * *